Stretch films are widely used in a variety of bundling and packaging applications, for example, bundling goods for shipping and storage. Stretch films or stretch cling films having high cling properties are particularly useful because the high cling helps prevent unraveling of the film from the bundled goods. As the film is stretched, however, localized deformation can result in a large fluctuation in elongation, giving rise to bands of weaker and more elongated film transverse to the direction of stretching, a defect known as “tiger striping.” Additionally, tiger striping is usually accompanied by a decrease in cling, which is undesirable.
To impart cling properties or to improve the cling properties of a particular film, a number of techniques have been used, including the addition of tackifying additives or “tackifiers.” Such tackifiers include polybutenes, low molecular weight polyisobutylenes (PIB), polyterpenes, amorphous polypropylene, ethylene vinyl acetate copolymers, microcrystalline wax, alkali metal sulfosuccinates, and mono- and di-glycerides of fatty acids. Current stretch films, however, still exhibit tiger striping and undesirable losses in cling upon stretching.
There is a need, therefore, for improved stretch cling films having improved cling after stretching and/or having reduced or no formation of tiger stripping during stretching of the film.